Ancient grouping of stars in same region of sky as dippers

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While most folks are familiar with the Big and Little Dipper, in the same region of the sky is a long, winding group of stars which portrays the mythological creature of a dragon named Draco, which during late evening hours is riding high above Polaris, the North Star.

Draco is a very ancient grouping. The earliest Sumerians considered these stars to represent the dragon Tiamat. Later it became one of the creatures that Hercules killed.

One of Draco’s tasks was to guard the garden of Hesperides and its golden apples that Hercules was supposed to retrieve. In the stars, Draco coils around Polaris and we now see Hercules standing (albeit upside down) on Draco’s head.

Within Draco is the star Alpha Draconis, better known as Thuban. Interestingly, this third-magnitude star used to be the North Star about 4,500 years ago. In fact, a passage in the Great Pyramid of Giza, constructed about that time, was aligned on that star. Today, of course, the North Pole of the sky is marked by the star Polaris at the end of the handle of the Little Dipper.

The location of the celestial poles changes slowly (over a period of about 25,800 years) owing to a movement of the Earth for which the pull of the Moon on a our bulging equator is chiefly responsible, a movement similar to the wobbling of a top known as precession. Look halfway between the bowl of the Little Dipper and the star Mizar (where the Big Dipper’s handle seems to bend) and there you will find Thuban, the former North Star.

The Dragon’s head is the most conspicuous part of Draco: an irregular quadrangle, not quite half the size of the Big Dipper’s bowl. The brightest star is Eltanin, a second magnitude star, shining with an orange tinge. Interestingly, a number of temples in Ancient Egypt were oriented toward this star.

The faintest of the four stars in the quadrangle however is worth looking for: Nu Draconis, a wonderful double star for very small telescopes. The two stars are practically the same brightness, both appearing just a trifle brighter than fifth magnitude and separated by just over one arc minute (or about 1/30th the apparent diameter of a full Moon). They’re about 120 light years away, and it is estimated that they are at least 240 billion miles apart – or about 2,300 times the distance of the Sun to the Earth.

I first stumbled across Nu as a teenager in the Bronx, using low power on a 4¼-inch Newtonian reflecting telescope. I liken them to a pair of tiny headlights. Check it out for yourself.